(Re)discovering the SPL - IPC14

Transcript

1. 1 Joshua Thijssen jaytaph (Re)discovering the SPL
2. 2 Q: Have you ever used the SPL?
3. 3 Q: Have you ever used the SPL without going nuts?
4. 4 SPL Documentation
5. 4 SPL Documentation http://www.php.net/spl
10. ➡ Not enough documentation. 7
11. ➡ Not enough documentation. ➡ Very few examples. 7
12. ➡ Not enough documentation. ➡ Very few examples. ➡ Wrong / missing in some cases. 7
13. ➡ Interfaces ➡ Iterators ➡ Data structures ➡ Exceptions ➡ Miscellaneous functionality 8 Every SPL talk available:
14. 9 Don’t get scared! The SPL is awesomesauce!
15. 10 INTERFACES
16. 11 Traversable (not an “spl interface”)
18. ➡ Traversable cannot be implemented. 12
19. ➡ Traversable cannot be implemented. ➡ Traversable can be detected (instanceof). 12
20. ➡ Traversable cannot be implemented. ➡ Traversable can be detected (instanceof). ➡ foreach() detects traversable interfaces and does magic. 12
21. 13 Iterator (still not an “spl interface”)
22. Userland interface to make an object traversable 14
23. Iterator extends Traversable { /* Methods */ abstract public mixed current ( void ) abstract public scalar key ( void ) abstract public void next ( void ) abstract public void rewind ( void ) abstract public boolean valid ( void ) } 15 Iterator interface:
24. ➡ Iterator ➡ FilterIterators ➡ “Chains” iterators together ➡ IteratorAggregate 16
25. $dir = opendir("."); while (($file = readdir($dir)) !== false) { # Business logic happens here print "file: $file\n"; } Let’s read directory content 17
26. $dir = opendir("."); while (($file = readdir($dir)) !== false) { # hack: only display mp3 files if (! preg_match('|\.mp3$|i', $file)) { continue; } # Business logic happens here print "file: $file\n"; } 18 Filter on *.mp3
27. ➡ Filter all MP3 and all JPG files. 19
28. ➡ Filter all MP3 and all JPG files. ➡ Filter all MP3 files that are larger than 6MB. 19
29. ➡ Filter all MP3 and all JPG files. ➡ Filter all MP3 files that are larger than 6MB. ➡ Do not filter at all. 19
30. ➡ Filter all MP3 and all JPG files. ➡ Filter all MP3 files that are larger than 6MB. ➡ Do not filter at all. ➡ Search sub-directories as well. 19
31. ➡ Filter all MP3 and all JPG files. ➡ Filter all MP3 files that are larger than 6MB. ➡ Do not filter at all. ➡ Search sub-directories as well. ➡ Search multiple directories. 19
33. ➡ How to test? (we can’t) 20
34. ➡ How to test? (we can’t) ➡ How to maintain? (we can’t) 20
35. ➡ How to test? (we can’t) ➡ How to maintain? (we can’t) ➡ How to reuse? (we can’t) 20
36. $it = new DirectoryIterator("."); foreach ($it as $fi) { print "File: ".$fi->getPathname()."\n"; } 21 Directory Iterator
37. $it = new DirectoryIterator("."); $it2 = new RegexIterator($it, "/\.mp3$/i"); foreach ($it2 as $fi) { print "File: ".$fi->getPathname()."\n"; } 22 Directory Iterator + filtering
38. $it = new DirectoryIterator("."); $it2 = new RegexIterator($it, "/\.mp3$/i"); $it3 = new FilesizeIterator($it2, 0, 6 * 1024 * 1024); $it4 = new LimitIterator($it3, 10, 5); foreach ($it4 as $fi) { print "File: ".$fi->getPathname()."\n"; } 23 Iterator chaining
39. $it = new DirectoryIterator("."); $it2 = new RegexIterator($it, "/\.mp3$/i"); $it3 = new FilesizeIterator($it2, 0, 6 * 1024 * 1024); $it4 = new LimitIterator($it3, 10, 5); foreach ($it4 as $fi) { print "File: ".$fi->getPathname()."\n"; } 23 Iterator chaining
41. ✓ Reusable We can use iterators where ever we want. 24
42. ✓ Reusable We can use iterators where ever we want. ✓ Testable Iterators can be tested separately. 24
43. ✓ Reusable We can use iterators where ever we want. ✓ Testable Iterators can be tested separately. ✓ Maintainable No need to adapt our business logic. 24
44. 25 Countable (hurrah! An “spl interface”!)
45. class myIterator implements \Iterator { ... } $a = array(1, 2, 3); $it = new myIterator($a); print count($it); 26
46. class myIterator implements \Iterator { ... } $a = array(1, 2, 3); $it = new myIterator($a); print count($it); 1 26
47. class myCountableIterator extends myIterator implements Countable { function count() { return count($this->_elements); } } $a = array(1, 2, 3, 4, 5); $it = new myCountableIterator($a); print count($it); 27
48. class myCountableIterator extends myIterator implements Countable { function count() { return count($this->_elements); } } $a = array(1, 2, 3, 4, 5); $it = new myCountableIterator($a); print count($it); 5 27
49. class myCountableIterator extends myIterator implements Countable { function count() { return count($this->_arr); } } $a = array(1, 2, 3, 4, 5); $it = new myCountableIterator($a); $it2 = new limitIterator($it, 0, 3); print count($it2); 28
50. class myCountableIterator extends myIterator implements Countable { function count() { return count($this->_arr); } } $a = array(1, 2, 3, 4, 5); $it = new myCountableIterator($a); $it2 = new limitIterator($it, 0, 3); print count($it2); 1 28
51. 29 SeekableIterator
53. ➡ It’s not an iterator, it’s an interface. 30
54. ➡ It’s not an iterator, it’s an interface. ➡ seek() 30
55. ➡ It’s not an iterator, it’s an interface. ➡ seek() ➡ Implementing “seekableIterator” can speed up other iterators. 30
56. ➡ It’s not an iterator, it’s an interface. ➡ seek() ➡ Implementing “seekableIterator” can speed up other iterators. ➡ LimitIterator makes use of “seekableIterator” 30
57. 31 ITERATORS
58. SPL Iterators ➡ AppendIterator ➡ ArrayIterator ➡ CachingIterator ➡ CallbackFilterIterator ➡ DirectoryIterator ➡ EmptyIterator ➡ FilesystemIterator ➡ FilterIterator ➡ GlobIterator ➡ InfiniteIterator ➡ IteratorIterator ➡ LimitIterator ➡ MultipleIterator ➡ NoRewindIterator ➡ ParentIterator ➡ RecursiveArrayIterator ➡ RecursiveCachingIterator ➡ RecursiveCallbackFilterIterator ➡ RecursiveDirectoryIterator ➡ RecursiveFilterIterator ➡ RecursiveIteratorIterator ➡ RecursiveRegexIterator ➡ RecursiveTreeIterator ➡ RegexIterator ➡ SimpleXMLIterator 32
59. SPL Iterators 33 http://lxr.php.net/xref/PHP_5_5/ext/spl/internal/
61. ➡ IteratorIterator? 35
62. ➡ IteratorIterator? ➡ RecursiveIterator? 35
63. ➡ IteratorIterator? ➡ RecursiveIterator? ➡ RecursiveIteratorIterator? 35
64. ➡ IteratorIterator? ➡ RecursiveIterator? ➡ RecursiveIteratorIterator? ➡ RecursiveCallbackFilterIterator? 35
65. ➡ IteratorIterator? ➡ RecursiveIterator? ➡ RecursiveIteratorIterator? ➡ RecursiveCallbackFilterIterator? 35
66. 36 IteratorIterator
67. 37 Turns traversable “things” into an iterator
68. 38 $it = new myIterator(); if ($it instanceof \IteratorAggregate) { $it = $it->getIterator(); } $it2 = new \LimitIterator($it, 5, 10);
69. 39 $it = new myIterator(); $it2 = new \IteratorIterator($it); $it3 = new \LimitIterator($it2, 5, 10);
70. 40 Recursive*Iterator
71. 41 $it = new ArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”)); foreach ($it as $v) { print $v . “\n”; }
72. 41 $it = new ArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”)); foreach ($it as $v) { print $v . “\n”; } foo bar Array baz
73. 42 $it = new RecursiveArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”)); foreach ($it as $v) { print $v . “\n”; }
74. 42 $it = new RecursiveArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”)); foreach ($it as $v) { print $v . “\n”; } foo bar Array baz
75. 43 $it = new RecursiveArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”)); $it2 = new RecursiveIteratorIterator($it); foreach ($it2 as $v) { print $v . “\n”; }
76. 43 $it = new RecursiveArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”)); $it2 = new RecursiveIteratorIterator($it); foreach ($it2 as $v) { print $v . “\n”; } foo bar qux wox baz
77. 44 “Recursive” iterators add the POSSIBILITY to recursively iterate over data. You still need to implement it!
78. 45 RecursiveCallbackFilterIterator
79. ➡ Enables recursivity ➡ Is a filter iterator (does not necessarily return all the elements) ➡ Filters through a callback function. 46
80. 47 CachingIterator
81. 48 2 for the price of 1
82. 49 ➡ Lookahead iterator ➡ Caches values, but not really :( ➡ Powerful __tostring() functionality (which probably no one uses)
83. 50 $alphaIterator = new ArrayIterator(range("A", "Z")); $it = new CachingIterator($alphaIterator); foreach ($it as $v) { if (! $it->hasNext()) { print "last letter: "; } print $v . "\n"; } // A // ... // Y // last letter: Z
84. 51 $alphaIterator = new ArrayIterator(range("A", "Z")); $it = new CachingIterator($alphaIterator); foreach ($it as $v) { if (! $it->hasNext()) { print "last letter: "; } print $v . "\n"; } print "The fourth letter of the alphabet is: ".$it[3]."\n";
86. ➡ Don’t change cached data (you could, but don’t) 52
87. ➡ Don’t change cached data (you could, but don’t) ➡ It doesn’t use the cached data on consecutive calls to the iterator. 52
88. ➡ Don’t change cached data (you could, but don’t) ➡ It doesn’t use the cached data on consecutive calls to the iterator. ➡ It clears the cache on a rewind() (and thus, a next foreach() loop) 52
89. 53 SPL Iterators,..
90. ➡ It has “quirks” that are easily solvable (but breaks BC) ➡ Documentation is not always up to date. ➡ Naming is VERY confusing (caching iterator, recursiveIterator, seekableIterator) ➡ But the iterators are worth it! 54
91. 55 DATA STRUCTURES
92. 56 ➡ SplDoublyLinkedList ➡ SplStack ➡ SplQueue ➡ SplHeap ➡ SplMinHeap ➡ SplMaxHeap ➡ SplPriorityQueue ➡ SplFixedArray ➡ SplObjectStorage
93. 57 ➡ Every data structure has its strength and weaknesses. ➡ Big-Oh O(1), O(n), O(log n) etc... ➡ Balance between time (CPU) and space (memory) ➡ PHP arrays are quite good! ➡ But sometimes other data structures are better.
94. 58 PubQuiz
95. 59 http://www.flickr.com/photos/sostark/26697448/
96. 59 http://www.flickr.com/photos/sostark/26697448/ SplStack
98. 60 SplQueue
99. 61 http://www.flickr.com/photos/blogchef/4764248456/sizes/z/in/photostream/
100. 61 http://www.flickr.com/photos/blogchef/4764248456/sizes/z/in/photostream/ Spl(Doubly)LinkedList
101. 62 http://www.flickr.com/photos/pediddle/54326823/
102. 62 http://www.flickr.com/photos/pediddle/54326823/ SplObjectStorage
104. 63 SplPriorityQueue
105. 64 http://farm4.static.flickr.com/3224/3072017987_ee454536da.jpg
106. 64 http://farm4.static.flickr.com/3224/3072017987_ee454536da.jpg SplHeap
107. 65 http://en.wikipedia.org/wiki/File:USA.NM.VeryLargeArray.02.jpg
108. 65 http://en.wikipedia.org/wiki/File:USA.NM.VeryLargeArray.02.jpg SplFixedArray
109. 66 ➡ Use wisely: ➡ Don’t use SplStack / SplQueue for random reads. ➡ Don’t use FixedArrays when you need speed boosts.
110. 67 EXCEPTIONS
111. ➡ BadFunctionCallException ➡ BadMethodCallException ➡ DomainException ➡ InvalidArgumentException ➡ LengthException ➡ LogicException ➡ OutOfBoundsException ➡ OutOfRangeException ➡ OverflowException ➡ RangeException ➡ RuntimeException ➡ UnderflowException ➡ UnexpectedValueException 68
112. ➡ BadFunctionCallException ➡ BadMethodCallException ➡ DomainException ➡ InvalidArgumentException ➡ LengthException ➡ OutOfRangeException 69 Logic Exceptions Runtime Exceptions ➡ OutOfBoundsException ➡ OverflowException ➡ RangeException ➡ UnderflowException ➡ UnexpectedValueException
113. 70 function foo($str) { if ($str == “The Spanish Inquisition”) { throw new \UnexpectedValueException(“Nobody expects ”.$str); } ... }
114. 71 function foo($str) { if ($str == “The Spanish Inquisition”) { throw new \InvalidArgumentException(“Nobody expects ”.$str); } ... } Logic, not runtime
115. 72 function foo($str, $int) { if (! is_string($str)) { throw new \InvalidArgumentException(“Invalid type”); } if ($int < 0 || $int > 10) { throw new \OutOfRangeException(“should be between 0 and 10); } ... }
116. 73 Never throw “\Exception” Always catch “\Exception”
117. 74 MISC
118. ➡ SPL Autoloading ➡ SplFileInfo class ➡ Spl(Temp)FileObject ➡ ArrayObject ➡ SplObserver / SplSubject 75
119. 76 Autoloader
120. 77 spl_autoload_register(“spl_autoload_call”);
121. 77 spl_autoload_register(“spl_autoload_call”); Throws logicException
122. 78 spl_autoload_unregister(“spl_autoload_call”);
123. 78 spl_autoload_unregister(“spl_autoload_call”); - Removes ALL the autoloaders! - Destroys the autoload stack. - Set your house on fire.
124. 79 ArrayObject
125. 80 ArrayObjects are not objects that acts like arrays ArrayObjects are objects that acts like arrays
126. 81 $a = array("foo", "bar"); $b = $a; $b[] = "baz"; print_r ($a); print_r ($b);
127. 81 $a = array("foo", "bar"); $b = $a; $b[] = "baz"; print_r ($a); print_r ($b); Array ( [0] => foo [1] => bar ) Array ( [0] => foo [1] => bar [2] => baz )
128. 82 $a = new ArrayObject(); $a[] = "foo"; $a[] = "bar"; $b = $a; $b[] = "baz"; print_r (iterator_to_array($a)); print_r (iterator_to_array($b));
129. 82 $a = new ArrayObject(); $a[] = "foo"; $a[] = "bar"; $b = $a; $b[] = "baz"; print_r (iterator_to_array($a)); print_r (iterator_to_array($b)); Array ( [0] => foo [1] => bar [2] => baz ) Array ( [0] => foo [1] => bar [2] => baz )
130. 83 How can we make using the SPL easier? http://noscope.com/photostream/albums/various/I_Want_To_Believe_01.jpg
131. 84 ➡ The (first and only) book about the SPL. ➡ Written by me (so you know it’s good :P) ➡ Fixes the documentation problem of the SPL (or a wobbly table)
133. ➡ Adaption of the SPL will only happen when developers can become familiar with it. 85
134. ➡ Adaption of the SPL will only happen when developers can become familiar with it. ➡ There is currently no real way to familiarize yourself with the SPL. 85
135. ➡ BLOG! ➡ Update documentation. ➡ Find the quirks (and maybe even solve them). 86
136. http://farm1.static.flickr.com/73/163450213_18478d3aa6_d.jpg 87
137. 88 Find me on twitter: @jaytaph Find me for development and training: www.noxlogic.nl Find me on email: jthijssen@noxlogic.nl Find me for blogs: www.adayinthelifeof.nl